While the clamps of the present invention may find application wherever one element is to be mounted on another by a clamping action, they are particularly well adapted for mounting the tooling on the ram and bed of a press brake. Therefore, for purposes of a non-limiting exemplary showing, the clamps of the present invention will be described in association with the ram and bed of a press brake.
With the exception of adjustable female dies, multiple groove dies and the like, most dies used on a press brake are provided with longitudinally extending tongues by which they are clamped to the ram and bed of the press brake. Exemplary dies of this type include acute angle dies, bottoming dies, flattening dies, air bend dies, gooseneck dies, radius dies, offset dies, beading dies, and many dies for special shapes.
In a typical prior art arrangement, the ram working edge is configured to present a forward facing clamping surface. The ram working edge is further configured to accommodate one or more longitudinally extending clamping bars. When more than one clamping bar is provided, they are arranged along the ram working edge in end-to-end alignment. The clamping bars provide a rearwardly facing clamping surface. The clamping bar or bars are adjustably affixed to the ram by bolts. The rearwardly facing clamping surface of the bars and the forwardly facing clamping surface of the ram edge define a slot of adjustable width into which the tongue of an appropriate die can be located and clamped by tightening of the clamping bar bolts.
In the most usual practice, the working edge of the press brake bed has a filler block appropriately mounted thereon and extending longitudinally thereof. The filler block provides a longitudinal groove in its upper surface adapted to receive the tongue of an appropriate die to be mounted on the bed. The filler block is provided with a plurality of transversely extending set screws, communicating with the filler block slot and adapted to be tightened against the die tongue located in the filler block slot to clamp the tooling therein. It will be immediately evident that the mounting and dismounting of dies from the press brake ram and bed, and the changeover from one die set to another, constitute time consuming and difficult operations.
The present invention is based upon the discovery that if the ram and bed are provided with hydraulically actuated clamping means, the mounting and dismounting of dies, and the changeover from one die set to another, can be accomplished quickly, easily and accurately. The clamps of the present invention are extremely simple in construction. The clamp for the press brake bed also serves as a filler block. The clamp for the ram is preferably an integral part of the ram. The ram clamp, on the other hand, can be a separate member attachable to the ram, for use on already existing press brakes.
A fundamental advantage of the clamping means of the present invention lies in the fact that they are mechanically biased to their clamping condition and hydraulically actuated to their unclamping condition. Thus, a failure in the hydraulic system cannot surprisingly release the tooling resulting in injury to the operator or damage to the press brake, the tooling, or the workpiece. Furthermore, hydraulic pressure need not be maintained during normal operation of the press brake, which is costly. Hydraulic pressure need only be maintained when tooling is released for changing.